This invention relates generally to the making of ophthalmic lenses and more particularly concerns calibration of machines used to cut/grind ophthalmic lens blanks.
A recent design of a machine for cutting/grinding ophthalmic lenses described in detail in a copending U.S. patent application is illustrated in FIG. M. The machine cuts/grinds an ophthalmic lens L which is chucked to the upper end of a first spindle which is in turn aligned on a Z-axis. One motor M1 rotates the lens spindle and the chucked lens blank L about the Z axis while another motor M2 reciprocates the lens spindle and the chucked lens blank L along the Z axis. A cutting/grinding tool T is mounted on the lower end of second spindle which is aligned on an axis A angled, preferably obtusely, with respect to the Z-axis. A third motor M3 rotates the tool spindle and the tool T about the angled axis A while a fourth motor M4 reciprocates the tool spindle and the tool T along an X-axis. A microprocessor P coordinates the rotation of the spindles about the Z and A axes and the reciprocation of the spindles on the Z and X axes to cause the tool T to cut/grind the lens blank L in accordance with its predetermined contour. Manual adjustment of the alignment of the tool T on a Y-axis perpendicular to the X and Z axes is possible.
Among the purposes of this machine are the minimization of calibration and tuning of the machine, accomplished in part because the lens thickness is a function of vertical lens movement only and in part because the operation of the machine is controlled by a single microprocessor.
While the machine described achieves this purpose very well in comparison to previously known machines, calibration is still an iterative process. Thus, while the number of parameters to be iteratively adjusted have been minimized by the machine, it is further desirable to minimize the number of iterations required for each parameter.
It is, therefore, an object of this invention to provide a gauge and method which provides Cartesian information suitable for calibration of a lens cutting/grinding machine. Another object of this invention is to provide a gauge and method which afford complete Cartesian calibration information as a result of a single operation of the machine.